Feed device for rotary beater mills with means for preventing blow-back of material



2,530,313 FOR ROTARY BEATER MILLS WITH MEANS Nov. 14, 1950 c. D. PARTENFEED DEVICE FOR PREVENTING BLOW-BACK OF MATERIAL Filed June 2, 1947..-D7/J. w

Patented Nov. 14, v1950 FEED DEVICE FOR ROTARY BEATER MILLS WITH MEANSFOR PREVENTIN G BLOW- BACK OF MATERIAL Carl D. Parton, Minneapolis,Minn., assignor to Schutz-@Neill Co., Minneapolis, Minn., a, corporationof Minnesota Application June 2, 1947, Serial No. 751,846

l Claim.

rlhig invention relates to a device for grinding solids to a fine stateof subdivision. More particularly, it relates to an improved mountingfor the parts of the VVgrinding machine and to improved means forrsupplying material to be ground to the grinding chamber.

In the grinding mills `'of the screen type as heretofore known,vexcessive vibration and wear of the parts has been a common experience.Another difculty in suchdevices is found in the means for supplyingmaterial to be ground to the -grinding chamber. The means for supplyingmaterial in the grinders heretofore known, particularly in hammer millsof the screen type, has been a simple hopper of decreasingcross-sectional area, which merely directs the material to be groundinto the chamber. With hoppers of this type, there is considerablethrowing back up into the hopper of material supplied tothe grindingchamber lunless the rate of feed of material to the grinding chamber is-kept low, not to mention the other obviousdisadvantages of such astructure.

An object is to provide agrinding machine such las a hammer Ymillpulverizer -of the screen vtype having improved means for supplyingmaterial to be ground -to Athe grinding -chamber whereby the capacity ofthe ymill is increased. -1

A f-u'rther `object is to provide a hammer mill pnlverizer of the4scr-een type lincluding means-for suppl-ying material to be lground -tothe grinding chamber in which material thrown lback from the grindingchamber is caught and returned to ,the grinding `chamber without.escaping into the atmosphere. -Y Y .therv objects will :appearhereinafter.

yEhe means by which-the lforegoing objects have been accomplished vareembodied in -the illustrative devices show-n inthe accompanying drawingswhich forma partofithis specification rand in which.:

Figure 1 is a view, partly in central vertical cross-section, of afpul-ver'izer embodying'features of the present invention;

Figure l2 isa vertical cross-sectional view -on the line 2?-2 in Figurel.; Y

Figures 3, 4, t5 and Y6 are views similar to Figure 2 showing .modifiedforms of feeding means.

As shown in Figure l, the rgrinding machine .generally-designated Itincludes a base I2 having a passageway I4 extending longitudinallythereof between a grinding-chamber I 6 at one end and a rblower chamberi8 at the other. Formed integrally with the ibase at each end thereofare verticallyxtend'ing walls i250 and l2|2 and associated (Cl. ,ZU-186)walls 24 and 26 extending at right angles thereto, which 'partly enclosethe lower portion of the chambers l and I8. The walls 20 and 22 Vbothterminate about midway of the chambers I6 and 'I8 respectively, and areprovided 'at their upper edges with flanges l2| and 23. 'Ihe upperportion of the chambers I6 ,and I8 is partially enclosed by a `pair ofsemi-cylindrically housings 25 and 21, open on one end. These housings25 and 21 are flanged as at 29 Aand 3| along their lower edges, and aresecured kin place by fastening means extending Athrough the respectivepairs of vflanges 29-2I `'and 3 I23. The closure-of chambers I6 and I8is completed by plates 28 and 30 respectively, which are bolted toflangesv32,133, 34, and 35, formed respectively on housing '25, `baseI2, housing 21 andzbase I2.

A pair of bearings 36 and 38 are mounted on the :base I2 between thewalls 2U and 22. The shaft 40 is rotatably mounted on these bearings.

.At yone end in the chamber I5 the shaft 4D has a set of three discs '42fixed thereon. These discs carry hammers or beaters 44. On the other endof the shaft 40 in chamber I8 a set of blower lblades 46 is fixed onshaft 4l). Between the bearing members'SB and 3B the shaft 4U carries adriving pulley 4:8.

The balance obtained in this structure is readily apparent .from thedrawings. By having the driving pulley 48 mounted in the center of theVshaft 40, the two driven members on either end and the bearings betweenthe driving pulley and the respective driven members, as nearly aperfect balance as possible is obtained. The central location of thebearings also contributes to improved `operation of this pulverizer, andthe fan and beaters are readily accessible.

As indicated above, the pulverizer which forms the subject 'of thisinvention, in 'addition to the improved arrangement of the parts, isalso pro- 'avided with inovel means for feeding material to be rgroundinto the 'grinding chamber. In general, the feeding means shown inFigures 2 ithrfough '6 are :characterized by the feature that theypermit material supplied to the grinding 'chamber .to be 'thrown backwithout permitting the rmaterial so thrown back Vto escape into theatmosphere.

In the embodiments Yof Figures 2 and '3, it -will be seen that thematerial to be ground is 'fed :into Ithe grinding fchamber in :agenerally radial direction, whereas in Figures 4, 5 and 6 the materialto .be :ground is fed into the :grinding zchamberin a :direction which:is substantially tangential :to the rotating 'grinding'memben "ruga'tedsection 14.

ing 25, a portion 5B extending vertically upwardlyv c from the portion54, another portion 58 extending horizontally from the vertical portion55, and nally, a portion 6U which extends upwardly at an angle of about45 from the horizontal portion 58. The open end of the portion 54is-provided with a flange 62 which is secured to the housing 25 by anysuitable means, such as welding. At the junction of the horizontalportion 58 and the vertical portion 55 a semi--circular baille 64 issecured within the horizontal section 53 to completelyl block the upperhalf thereof. Material to be ground is first filled into the portion B5of the conduit. Feed of material in the portion 65 is controlled by anadjustable feed gate 66 mounted in the portion 55. The gate 55 isslidably mounted in a slotted guide 58 secured to the conduit member .55with its slot in alignment with a corresponding slot through conduitsection 52. 'mounted in the guide 68 permits the feed gate A set screw19 65 to be secured in any desired position.

As indicated by the arrow 12 in Figure 2, the

vdiscs 42 in the embot'iment oi' the invention shown in 1Figure 2 rotatein a clockwise direction when viewed from the end of the shaft 45 onwhich these discs Vare mounted. Material sup- Ltion 14 which may beremovable is secured to 4the inner surface of the annular wall portion15 oi the housing 25 between the opening 55 and the lower end of thewall portion 15 on the other side' of chamber I 6.

" 'The maximum size of ground material leaving "thegrinding chamber I5is determined by a 'screen 18 mounted in the lower portion of thechamber. The screen 18 is provided at its upper rend with flanges 85andl 52 which are secured' at either side of chamber IB between flangesand 2I, which are suitably relieved at these points to ac'commodate theflanges 85 and 82. "the vertical wall 2B and the end plate 28 a pair ofBetween side walls 84 and 86 extend inwardly and clown- Ywardly from thevertical walls 24 and join a bot'- tom wall 88 'of base I2, which is acontinuation ``r; .of the lower wall of the conduit I4. rIhese wallscomplete the closure of the chamber I6. The lower portion of chamber I6opens into the conduit I4 through an opening B0 formed in the verticalwall 20.

In the operation of a pulverizer embodying the features illustrated inFigure 2, material to be kground is lled into the conduit portion Ell,the

feed gate 66 is positioned to give the desired rate of feed, and thematerial to be ground passing s beyond this gate proceeds through thehorizontal conduit 58 past the baille 64, downwardly through thevertical conduit 56, and then through the radially extending conduit 54,and enters the chamber I6 through the opening 50. The hammers 44 aremoving in the direction indicated by -the arrow 12, and they pick up thematerial entering chamber IB and throw it against the cor- In thismanner the large pieces of solid material are disintegrated or pul- 4verized, and as they are carried around by the rotating grinding member,they are eventually brought to the screen 18 through which a portion ofthe material which is line enough passes. A ian such as the fan 46 pullsair through the conduit I4 from chamber I5, drawing with it the groundmaterial passing the screen 18, The air carrying the ground material isdischarged through the exhaust 52 of the fan 46 to suitable collectionmeans. By reason of the construction of the conduit 52, it is possibleto operate under conditions such that a considerable portion of thematerial supplied to the chamber I6 is blown back through the opening5I), as, for example, by rotating the hammers 44 at relatively highspeed or by supplying material to be ground to the grinding chamber at arelatively high rate. The advantage of operating under conditions wherea lot of material is blown back through the opening 5B is that maximumgrinding capacity is obtained under these conditions, that is to say,the

grindingcapacity of a given unit increases within certain limits as theamount of material blown back through the opening increases. Inpreviously-known pulverizers it was not possible to operate with anysubstantial amount of blowback through the opening into the grindingchamber because the material so blown back escaped to the atmosphere andwas'lost or else forced fresh material being supplied to the grinder tobe thrown into the atmosphere and lost, or both. These losses areprevented by the conduit 52. The velocity of material blown back throughthe opening 55 is spent. by impact with the Walls of the conduitportions 54 and 55 particularly. Material deflected by these walls iscaught, at least in part, by the baille 64. Any small amount whichescapes past the baille 64 spends itself against the feed gate 66 or iscaught and carried back toward the chamber I6 by the material beingsupplied to the grinder through the conduit portion 65. This materiallmoving through theporand thus takes the place of portions 54 and 56 inthe conduit 52. 96 joins a horizontally-extending portion 98,

Vertically-extending portion which is in turnv joined by portion Itextending up at an acute angle. It will be seen that these latter twoportions correspond respectively to the portions 58 and 60 of conduit52. Material to be ground is supplied to the open end of the conduitIUD, and the rate of feed thereof toward the chamber IE is controlled byfeed gate |02, which, like the feed gate 56, is mounted in a slottedguide m4, secured to the conduit |50 in line with an openingtherethrough. Gate |52 is slidable in the guide |04 and may be securedin any desired position by the adjustment screw H16. The flange 08,formed on the open end of the conduit portion 96 is secured to thehousing 25 by welding or other suitable means. A baille I I0, identicalwith the baille 64, is secured inside the conduit at the junction of thevertical portion 86 andthe horizontal portion 98.

The direction of rotation of the hammers 44 in th'e embodiment of Figure3 is not material due to the central location of the opening 92. By wayof illustration, the arrow H2 is included tofshow that the hammers 44can )be rotated in a clockwise direction, as in the vembodiment ofFigure .2. A corrugated 'section v-I'I-4, simi-lar to the section 14, issecured to the annular wall 16. Due'to the location of the inlet to thechamber I6, it is necessary to lprovide an opening I'IG through thecorrugated section I I-4,^which is positioned in alignment with theopening 92. v Y The embodiment of Figure 3 is other-wise iden-Y ticalwith that of Figure 2. It includes the same .screen i3 having anges 8|]and B2, which are clamped bet-Ween the flanges 29 and 2| to hold :thescreen in place. It also .includes the wal-ls 84, 85, and B8, completingthe closure -of the bottom of the chamber, and it includes the opening9i) through the wall 2t. The operation of the .embodiment of Figure 3 isalso similar to that of VvFigure 2. Material to be ground, enter-ing thechamber I6 radially through the -openingsii and |46, is engaged by thehammers 44 and driven Vvagainst the corrugated Ysection .I I4. Groundmaterial eventually passes through the screen 18 and vis carried by acurrent of air through vthe conduit I4 and discharged-by a f-an 43-through an exhaust s2 to suitable collection means.

The main advantage of the embodiment shown in Figure 3,-as compared with-other embodiments, is that it is relatively easy to construct. There islslig-htly less blow-back -in this form under otherwise equivalentconditions. Material which vis Vblown back through the openings 92 andH6 spends its force mainly against the walls -of conduit section ed andagainst the :bariile Iie'l. Any small amount of 'material which does`pass the ,baiiie IIS is caught by the gate |02 or the material movingpast the gate -in the manner already described above in connection withFigure 2.

The embodiment of Figure 4 :gives the maximum single pass grind; thatis., the maximum amount of grinding for a :single passage of materialthrough the pulverizer, and, accordingly, this .embodiment provides the`maxim-um capacity for a given size of machine. In Figli-ree the openingIi' in wall "It, through which material .to be ground is supplied to thechamber I5, like ythe opening till, is located just above the flange 29.It is of the proper size and shape to conform vwith the `verticalportion |20 `of the conduit |22, which directs the material to be groundinto the grinding chamber i5, through the opening I I'S in .a directionwhich is tangential to the path. of the movement of the hammers 44.Because this embodiment involves the maximum amount of blow-bach throughthe opening into chamber iii, the horizontal conduit section |24 joins`the vcrtical rportion |223 lintermediate its ends, thereby providing asurge chamber |25 in the upper part .of the vertical conduit portion|29. The size of this surge chamber .|25 is further increased by-thebailie |23, located at the junction ci the ver- Vtical conduit I andthe horizontal section |24. As in the other embodiments, the horizontalsec- .tion |24 in turn communicates with a portion l|355` extendingupwardly at an angle to the verztical. A flange i312, `formed on thelower end of the vertical portion |20, Ais secured by riveting orwelding or any other desired means to the housing 25 to hold the conduiti22 in place. A feed gate |34 is slidably mounted in a guide |35 securedto the conduit .portion |33 in alignment with an opening therethrough.An vadjustnflent screw 33 permits the gate |34 to be secured inany-desired position.

Figure 4. also illustrates a feature of construction lwhich can beincluded .with `any .of the .em-

bodiments yshown iinaarry offthe yother:iiguresnto provide :bettercontrol of lthe, head =of pressure o f .the material to'befground, whichis bein-g supplied through the conduit portion .130. ',Io. this end, theportion |30, :intowhich the material to .be ground is supplied, insteadof .being rigidly connected'to thehorizon-tal conduit. section |24,1spivoted thereto iat YI4!) at the` uppermost Ypoint off-the junction-ofthe two ysections and over lthe remainder of its :circumference is-slidably extendedwithin the horizontal portion |24, which, for vthispurpose, is vextended outwardly --.and curved upwardly aaswndicated at|42. In vthis wayithefsection |30 can be adjusted to various angles withthe vertical', at all of--which there -is a tight'j-om-t between.sections;|24.,and |30. It is apparent, of course, that with-*aggiveniamount of' material Yin the conduit T30, the'head of pressure Aat `feedgate |34 depends upon the angle with respect tothe vertical at which theportion i3d, egtends.- c g lrIhe embodiment of Figure 4 is particularlycharacterized by the fea-ture that the `material to be ground -is.supplied to the -chamber I6 tangentially in adirection .oppositegthatin which the hammers 44 lare :moving adjacent the inlet fIfIS.. T-hedirection of rotation of the hammers 44 is, accordingly, u'as indicatedbythe arrow |44. Between theinlet VI I8 `and the opposite-side of .thehousing 2.0;a corrugated section |46 is secured to the 4wall 1-6 tocooperate with hammers 44, as :inthe other-embodiments described above.The ylower half of the grinderstructure `is `identical with that in t-heother embodiments and has al-readybeen described above.

'The operation of vthe structure illustrated 1in Figure .4 is lasfollows: The conduit'section .|30jis set at the appropriate angle toprovide the desired head :at the feed gate |34. .Material supplied .tothe conduit section |139 moves .pa-st the feed gate ,4.34 through the1section V|24 and `thence downwardly to chamber4 |16.; After v:it isground, the material passes, as in the other embodiments, through screen18 land is eventually carried to a collection means by a current of air.It has already been pointed out above that this particular form givesmaximum feed-.back `through the opening IIS, and, accordingly,additional provision is made in the-conduit |22 tospend the force .ofthe material fed back and prevent ity V,from escaping to the`atmosphere. It is a particular advantage of this embodiment that thematerial being ground can be caused to feed back the larger particlesuntil they are broken up suinciently so that they :no longer Vhaveweight enough `to oppose the head of pressure of thefresh materialcoming in to be ground. In 'this manner, a sort of automatic separation-and .regrinding of the larger particles is obtained.`

In contrast `to the embodiment of Figure L4, that of Figure 5 provides aminimum of feedback. The opening :|48 `in the wall 16, through whichmaterial to be ground enters chamber I6, is located near the top of thehousing 25. Because of the flow feed-back, the conduit `.15.0, throughwhich material to .be ground is brought to the opening |48, is'relatively simple in structure. As may be seen, it vincludes a portion|52 extending generally tangentially with respect to the path of travelof the hammers 44 adjacent the opening |48. The Yportion V|52joinsfasecond portion |54, extending generally vertically. This portion|54 is shown as somewhat enlarged :in cross-sectional area over the.portion |52. In any of the embodiments shown,ithezporton .of

the conduitinto which the material to b'e ground 'is first supplied may,if desired, be considerably enlarged overl the remainder of the conduitand may include a hopper, if desired. To provide meansfor securing theconduit |50 to the housing 25, the open end of section |52 is providedwith a flange' |56, which is welded or otherwise fastened to housing 25about the opening |48. The conduit section |52 is provided with a feedgate structure which, like the others previously described, includes agate |58, a guide |68, and an'adjustment screw |62. Inthis embodiment,in which the hammers rotate in the direction in- 'dicated by the 'arrow|64, blow-back is largely or completely 'prevented by providing a baffle|66. Ihe baille |66 is shaped to close o the upper portion ofthe conduitsection |52 when it extends generally radially with respect to the discs42. As in the other embodiments, a corrugated section |68 is secured tothe Wall 16 of housing 25. An opening |10 is provided in the corrugatedsection |68 in alignment with opening |48. The lower half of thegrinding chamber structure, which is the same as that in the otherembodiments, has already been described.

The embodiment oi Figure 5 operates with a minimum of blow-back sincethe material to be ground, moving past the gate |58, enters the chamber|6 in a direction tangential to the path of movement of the hammers 44,and at its point of entry is moving in the same direction as thehammers. Actually, in this form the rotating hammers tend to pullmaterial into the chamber rather than to blow it back, as in thestructure of Figure 4. Any small amount of material which may tend toblow-back is caught by the baffle |66 and returned to chamber I6. Thus,in Figure 5, the blow-back problem is solved mainly by minimizing theamount of material which leaves chamber I6, rather than by providing acircuitous conduit in which the force of the material blown back maybespent against the walls.

:In the 'structure shown in Figure 6, the conduit |122 extends into thechamber |6 which is enlarged'by replacing the curved wall 16 of housingon one side with a vertical wall |14. The hammers move in the directionindicated by the arrow |13 and the Wall of conduit |12 thus serves' asa'bafe. Material being ground is thrown up into the space between thelower part of the Wall of conduit |12 and the vertical wall |14 and thenfalls back into the periphery of the mill again.

Plate 28 and wall 25 are extended out to the wall |14 to complete theclosure of chamber 6. Conduit |12 extends into chamber I6 at about thesame angle as conduit |58 through an opening |16. This conduit isgenerally the same in structure as conduit |50 and only the lowerportionzwhich differs is shown. A` corrugated section |80 similar instructure and mounting to those previously described is provided to aidin the pulverizing. The lower half of the grinding chamber is not shownsince it is the same as that in the other embodiments. In addition tothe differences noted, it is further pointed out that conduit |12 doesnot have a flange such as |56, and instead is secured to housing 25 andplate 28 by Welding as at |18 around the opening |16. Inthe embodimentof Figure 6 as in that of Figure 5, the feed back is low because thefeed is tangential in the direction of movement of the hammers whichtend to pull the feed into the chamber I6 and thus the conduit |12 givessufcient baffling effect.

This invention is not intended to be limited to any particular form ofrotating elements in the grinder structure. Instead of the hammers 44carried by discs 42, swinging hammers orother equivalent grinding meansmay be employed within the scope of the invention. It will also beunderstood that the invention is not intended to be limited to astructure in which the base has a passageway such as the passageway |'4,through which ground material is drawn oi.

'Ihe advantages of this invention will be apparent from the foregoingdescription. By locating the driving member in a central position withthe grinder on one end, and the fan blade on the other end of the mainshaft, a well-balanced structure is obtained. The balance of thestructure is also aided by the location of the two bearings between thedriving pulley 48 and the fan and grinder respectively. Such a balancedstructure has the advantage of decreasing vibration and at the same timedecreasing wear Yof the parts.

The various forms of conduit for supplying material to be ground to thegrinding chamber, as illustrated in Figures 2 to 6, solve the problem ofblow-back and thereby increase the capaciity of the grinder. Whether theblow-back is minimized by admitting material tangentially, as in Figures5 and 6, or is controlled as in the other embodiments, the capacity ofthe grinder is increased as compared with the conventional grindingmachine, in which material to be ground iscsupplied to the grindingchamber through a simple hopper structure. It will be apparent that thepulverizer disclosed herein is suitable for pulverizing a wide varietyof materials, such as, for example sugar and many other like materials.

It is apparent that many widely diierent embodiments of this inventionmay be made without departing from the spirit and scope thereof, and,therefore, it is not intended to be limited except as indicated in theappended claim.

I claim:

A grinding mill comprising a housing including a cylindrical top portionand providing an internal grinding chamber, a rotating hammer in saidchamber, an inlet opening in the top portion of said housing positionedin advance of the vertical center line through the chamber and close tothe rotating hammer with relatively small clearance therebetween andthrough which material to be ground is supplied, an outlet :for groundmaterial, and means for supplying the material to be ground to saidinlet opening and including a closed conduit having a relatively shortdownwardly inclined conduit portion with one end in communication withsaid inlet opening and extending substantially tangentially with respectto the path of movement of said hammer across the inlet opening andpositioned so that material moving from said conduit into the grindingchamber is travelling in substantially the same direction as therotating hammer, an upstanding conduit portion in communication with theopposite end of said inclined conduit portion and providing an abruptchange of direction for material being fed therethrough, an adjustablefeed gate positioned in the downwardly inclined conduit portion forcontrolling the flow of material therethrough, and a bafe depending fromthe upper wall of the said downwardly inclined conduit portion anddisposed between said feed gate and said inlet opening, said bafflebeing inclined in the direction of feed of the material through theinclined conduit portion and terminating substantially vertically aboveand adjacent the lower edge of said inlet opening whereby to close offthe upper part of the inclined conduit portion and to trap blown-backmaterial between the upper inclined edge of the baille and the adjacentwall surface of the inclined conduit portion above the inlet opening.

CARL D. PARTEN.

REFERENCES CITED The following references are of record inthe le of thispatent:

UNITED STATES PATENTS Number Number Name Date Y Koch June 14, 1927Hirsch July 26, 1927 Ward Apr. 2, 1929Y Ruprecht et al Apr. 30, 1929Farner Apr. 1. 1930, Frickey May 20, 1930A Shelton Mar. 31, 1931@ CragoMay 30, 1933` Myers May 29, 1934' Sherman July 23, 1935 Frisch May 26,1936 Barnes Jan. 18, 1938 FOREIGN PATENTS Country Date Great Britain of1871 Great Britain Nov. 6, 1905 France Jan. 21, 1921 Great Britain May9, 1935 Italy Apr. 22, 1932 Germany Apr. 20. 1933

